Characterization of metal removal of immobilized Bacillus strain CR-7 biomass from aqueous solutions.

Bacillus strain CR-7 of multiple metal and antibiotic resistances was isolated. Its metal adsorption under different pretreatments and immobilizations from aqueous solution was characterized. Pretreatment with NaOH (0.1 mol L(-1)) significantly improved Cu(2+) adsorption capacity of the bacterial biomass. Sodium alginate (2%) was the ideal immobilization matrix. The immobilized and pretreated biomass had an obvious "orderliness", following the order of Cu(2+)>Zn(2+) in the solution containing these two metals, and following the order of Pb(2+)>Al(3+)>Cr(6+)>Cu(2+)>Fe(3+)>Zn(2+) = Ni(2+)>Cd(2+) = Co(2+)>Mn(2+) in the solution containing these 10 metals. ΔH° and ΔS° of Cu(2+) adsorption were +7.68 J/mol and +16.628 J/mol K, respectively. The infrared peak of -N-H shifted greatly after Cu(2+) adsorption. After adsorption treatment, some molecular groups disappeared in un-immobilized biomass but were still present in the immobilized biomass. Cu(2+) adsorption fit both Langmuir and Freundlich isotherm models. It was concluded (1) that the Cu(2+) adsorption process was endothermic, (2) that -N-H is a most important Cu(2+)-binding group, (3) that immobilization prevents loss or damage of the Cu(2+)-binding molecular groups, and (4) that Cu(2+) adsorption of pretreated and immobilized biomass is homogeneous.